This sounds like something out of a sci-fi movie, but, alas, it is real: There are now radioactive Bluefin tuna swimming off the shores of the United States. How did they get that way? It happened as a result of the nuclear disaster at the Fukushima Dai-ichi reactors that was set off after the huge earthquake in Japan in March of last year.

After the radioactive contamination leaked into the ocean off the coast of Japan, scientists found that small fish and plankton had elevated levels of radiation, but they didn't expect it to stay in larger fish because they "metabolize and shed radioactive substances" as they migrate across the ocean. Nicholas Fisher, one of the researcher who reported the findings, said, "We were frankly kind of startled." Uh, that's never good when the topic at hand is nuclear fallout.

The level of radioactive material found in the large Bluefin tuna near California—which is 6,000 miles away from the site of the leak in Japan where they spawn before swimming east—was 10 times higher than has been measured in that spot previously. These fish, which can grow to weigh more than 1,000 pounds, apparently couldn't shed the radioactive material as fast as the scientists thought. Says Fisher, "That's a big ocean. To swim across it and still retain these radionuclides is pretty amazing." Yes, amazing or terrifying, take your pick!

And what's worse is that the fish tested for this report were not even exposed to the radioactive area for that long—only about a month. The next batch of fish coming across will have been exposed for far longer and could show even more contamination. As far as eating the Bluefin tuna, which is normally very prized and quite pricey, we aren't supposed to freak out. The levels they found are still well below the safe-to-eat limits allowed by the governments in both Japan and the U.S. Sure, but you should probably make your own decisions about just how radioactive is too radioactive when it comes to your dinner.